Display screen or portion thereof having a graphical user interface for a link to a data interface



The sole FIGURE is a front view of a display screen or portion thereof having a graphical user interface for a link to a data interface showing our new design.

The broken lines depict portions of the display screen or portion thereof having a graphical user interface for a link to a data interface in which the design is embodied that form no part of the claimed design. 

CLAIM The ornamental design for a display screen or portion thereof having a graphical user interface for a link to a data interface, as shown and described. 